Preservation of soap



Patented Mar. ii, 194? UNITED 'smes PRESERVATION OF SOAP George D. Martin, Nitro, W. Va... assignor to Monsanto Chemical Company, St. Louis, Mo., a corporation of Delaware No Drawing. ApplicationMarch 25, 1938,

. Serial No. 198,102

10 Claims.

This invention relates to the stabilization of compositions containing a fatty component and particularly to the prevention of their decomposition or rancidification.

It is an object of the present invention to stabilize, both as to color and odor, animal, fish and vegetable oils, fatty acids, fatty esters, fats, waxes and products formed therefrom including particularly soaps and soap products. Thus, in its broader aspects the present invention embraces the stabilization of those fatty materials, without regard to source, which are normally subject to oxidation and which are employable in the preparation of soap and soap products as well as the soap and-soap products themselves. In

c this application all of the unstable materials of the nature indicated above will be hereinafter referred to as oxidizable fatty materials. .By the term soap is meant the metal salts of fatty acids.

It is well known that soap, especially white soap, tends to deteriorate upon aging as evidenced by color and objectionable odor. These obnoxious characteristics are particularly noticeable in the case of soaps made from oils which themselves quickly become rancid, as for example cottonseed oil, palm oil, palm kernel oil, peanut oil and the like. Rancidity and color formation are known to be accelerated by various agents such as heat, sunlight, ultraviolet light and certain metals such as copper. It is desirable to counteract these accelerating agents and the natural tendency of oxidizable fatty materials to deteriorate with age a and attempts have been made to achieve these results by employing in such compositions materials having so-called antioxidant properties. However, the application of the usual antioxidants to preserve oxidizable fatty materials has not met with success. The fact that a good antioxidant for one type of composition may be useless in another is not readily explainable since the manner in which an antioxidant functions is not known. For the preservation of oxidizable fatty materials resort has been had to various acids which are ordinarily considered to exert little or no antioxidant influence as for example sulfuric acid, oxalic acid, peracetic acid, phosphorous acid, tartaric acid, phosphoric acid, etc.

It has now been discovered in accordance with the present invention that phosphorous esters, the term phosphorous hereinafter indicating trivalent phosphorus, are efiective stabilizers of oxidizable fatty materials, preserving the color, preventing rancid odor and in short, exhibiting a number of desirable properties. For example certain of the preferred class of antioxidants exert a slight bleaching action toward oxidizable fatty materials so that their incorporation in normally colorlass products results in a greater improvement than is attributable to antioxidant properties alone.

The compounds which comprise the present in-= vention are conveniently described by the following structural formula R-O- P Y where R is an organic radical in which carbon is directly linked to the oxygen of the above formula, X is halogen, OH, OR. or R, B. being an organic radical the same or difierent than R, and Y, which may be the same or different than X, is halogen, OH, OR or R, R being an organic radical and in addition Y may be attached to R forming a compound of the structure is to be found. Thus the invention includes compounds of the structure and likewise compounds of the structure Typical examples of the preferred class of soap stabilizers are phenyl phosphorous acid dichloride phenyl phosphorous acid p-hydroxy phenyl phosphorous acid dichloride p-hydroxy phenyl phosphorous acid monochloride m-hydroxy phenyl phosphorous acid dichloride, o-phenylene phosphorous acid chloride PCl 9/ beta naphthyl phosphorous acid dichloride (diamyl. p-hydroxy, phenyl) phosphorous acid dichloride, biphenyl phosphorous acid dichloride, tolyl phosphorous acid dichloride, chlorphenyl phosphorous acid dichloride, chlor phenyl ophenylene phosphite the salicylic acid ester of phosphorous acid chloride of the formula. according to R. Anschiitz and and W. Emery, Justus Liebig's Annalen der Chemie, vol. 239, page 304,

p-phenylene di(phosphorous acid dichloride) c1 di-o-tolyl phosphorous acid di-p-tolyl phosphorous acid phosphite triphenyl phosphite di-o-tolyl sodium phosphite PONa, di-o-tolyl ester of tolyl phosphinous acid ortho phenylene ester of tolyl phosphinous acid, di-butyl tolyl phosphite OBu the mono ethanol amine salt 0! tolyl phosphorous acid dichloride and the tri ethanol amine salt of tolyl phosphorous acid dichloride, tolyl o-phenylene phosphite, o-phenylene phosphite and tri ethyl phosphite.

Esters containing trivalent phosphorus, as exemplifled by the above examples, are well known compounds and are described in the chemical literature. In general the method of preparation is exemplified by reacting a phosphorous halide with an alkyl or aryl hydroxide to produce a mono or di halide phosphorous ester or further reacting said mono or di halide phosphorous ester to produce a neutral ester. More particularly, one convenient method for the preparation of phosphorous esters is by the reaction of phosphorous trichloride with phenols. This reaction was described by Scheid in 1883 who studied the reaction of phosphorus trichloride on dihydric phenols (Justus Liebis's Annalen der Chemie, vol. 218, page 207). The work has since been great- 1y extended and many compounds of a similar type have been described. The particular compound obtained is largely determined by the proportion or the reactants, for example either one, two or three mols of cresol will react with phosphorus trichloride. The number of possible reaction products is even greater in the case of polyhydric phenols since each hydroxyl group is capable of reacting independently with the phosphorus trichloride.

.lt will be noted that in the case of a mono or di halide phosphorous ester there is an opportunity for reacting further either with the phenol used in the original preparation or with other phenolic or alcoholic bodies or, as indicated in the above examples, with an amine .to form a salt. All such materials containing the typical groupx a-o-r are within the scope of the present invention. Where convenient or desirable and where the parent compound submits to such treatment, a mono or di halogen phosphorous acid ester may be hydrolyzed and the halogen replaced by OH. These compounds as for example di-o-tolyl phosphorous acid have likewise been found to be effective stabilizers of oxidizable fatty materials.

It is to be understood that other methods of preparing the preferred compounds may be employed where convenient or desirable as is readily apparent to those skilled in the art of synthetic chemistry. The general methods of preparation outlined above are merely those which have been found particularly convenient for obtaining certain of the compounds or the present invention and more particularly those which may be regarded as derivatives of phosphorous acid. P(OH) s, by replacing one or more hydrogens with an organic radical, the remaining OH groups being replaceable by halogen. Moreover, derivatives of phosphinous acid are likewise within the scope or the present invention. Flor example toluene was condensed with phosphorus trichloride in the presence of aluminum chloride to form 201 CH3P\ 01 which was further reacted with crescl thus replacing the halogen and forming a compound containing the typical grouping present in the compounds of this invention,

X being OR and Y being R.

The 1 following is a typical method employed in testing the preferred materials and is a specific embodiment of the invention showing the useful and valuable properties of the preferred class of compounds but one which is intended to illustrate the invention and in nowise to limit the same.

A substantially neutral soap was prepared by saponifying a mixture of substantially 3 parts of an edible tallow and substantially 1 part of cocoanut oil with sodium hydroxide. Substantially 0.1% based on the weight of the soap of one of the preferred stabilizers was incorporated therein by a suitable means. 'Five grams of the treat-. ed soap were placed in a 250. c. c. iodine flask, a piece of filter paper saturated with water was torn to small pieces and placed in the flask. The flask was then tightly stoppered and placed in an oven maintained at a constant temperature of 50 C. At the end of each day the color of the soap under test was noted, also the stopper was removed and any odor indicative of rancidity noted. Similar tests were carried out with the same soap but to which no stabilizer was added and the periods of stability compared. The'period during which the soap containing typical examples of the preferred class of materials did not develop rancidity or substantially discolor is given in the following table.

readily shown that the preferred class of compounds constitute an important class of soap stabilizers and embody a wide variety of phosphorous esters varying from distinctly acid to neutral esters.

As further specific embodiments of the present invention a convenient quantity, for example 0.01% to. 1.0% by weight of any of the above preferred class of stabilizing agents may be incorporated in a fatty acid compound such as animal or fish oils or a vegetable oil, for example cottonseed oil. As a means of testing the stabilizing action thereof, the treated oilis heated in an open flask for several days in an oven maintained at 50 C. After various intervals of time samples of the agedoils are tested in a manner Q11 and Soap, vol. 9, page 93, 1932'. Thus five grams of cottonseed oil are dissolved in 50 c. c. of solvent mixture (60 percent of glacial acetic acid, 4.0 percent of chloroform) and 1 c. c. of saturated potassium iodide solution added. After exactly one minute from the time of the addition of the potassium iodide, 100 c. c. of water are added and the liberated iodine titrated with 0.01 N sodium thiosulfate, employing starch as indicator. The titration in cubic centimeters is a measure of the peroxide formation and consequently a measure of the stability of the oil. The titration figures obtained on-heating the above 011 for different periods of time at 50 C. in the absence of and in the presence of 0.1% by weight of the new class of stabilizing agents is given in Table II.

Table II Titration in c. c. N/lOO N81820: after- Stabilizlng agent 4 days 11 days 16 days @150" 0- @50 0. @50O Blank 42.6 70.0 o-Phenylene phosphorous acid chloride 1. o v 1.0 1. 0 o-Chlor phenyl o-phenylene phos hits 2.0 2.0 1.1 ohenylene phosphite. 1. l 1. 0 1.0 Bu lo-lphenylene phcsphite 2. 4 2. 2 1. 5 Tri if phosphite l 6. 1 5. 8 9.1 p-Toly phosphorous acid dichlo- 1 7 1 7 1 6 mtoii13hos ""'1i8i5s'i1h'5i1o c loride 3. 7 8. 3 31. 0 o-Tolyl o-phenylene phosphite 3.0 4. 0 5. 0

Table I Percent stabilizing Period of Stabilizing agent agent based stability on weight in days of the soap o-Chlor phenyl o-phenylene phosphite.- 0. l l 10 Salg yli c:i acid ester of phosphorous acid 0 l 14 c or e Hydroxy phenyl phosphorous acid dlii:hlioride 615.--}...fi.-- .f)- 005--- 0. 1 13 roxy to en os oro r lirlnridn y y p 9 0, 15 o-Bi henyl phosphorous acid dichloride-.. 0. 1 l3 o-To yl phosphorous acid dichloride 0. 1 .13 Di-o-tolyl phosphorous acid monochloride. 0. l 42 g'lolyl phosphorous acid dichloride 0. l 13 i-p-tolyl phosphorous acid monochloride- 0. l 45 Tri-o-tolyl phosphite 0. L 17 Tri henyl phosphite-.. 0.1 0 C or to yl hosphorous acid dichloride.-- 0. 1 l1 Di-(chlor to l) phosphorous acid monoo?tii"r"t "a 8'} it -op osp orous ac Di-o-tol l sodium phosphite 0. 1 14 Benz 1 lyl phosphorous acid dichloride 0. 1 l4 Di-oolyl ester of to! l phosphinous acid-. 0. l 13 Di hutyl tolyl phosp ite 0. 1 9 Mono ethanol amine salt of o-tolyl phosphorous acid dichloride 0. l 18 ri ethanol amine salt of o-tolyl phosphorous acid dichloride 0. 1 13 From the data set forth in Table 11 it is shown that the preferred class of compounds possess exceptional stabilizing properties when incorporated ln oxidlzable fatty materials, for example vegetable oils.

Examination of the new class of stabilizers in a variety of oxidizable' fatty materials showed the general applicability of organic phosphorous esters to the stabilization of oxidizable fatty compositions. For example olive oil, cocoanut oil and peanut oil were prevented from going rancid for extended periods of time by theincorporation of smalLamounts of the new antioxidants. Peanut oil which went rancid in 18 days at 50 C. was preserved 253 days by the incorporation of 0.1% by weight of o-chlor phenyl o-phenylene 'phosphite. The incorporation of 0.1% by weight of o-phenylene phosphorous acid chloride prevented the rancidity in the same peanut oil for 425 days and at the end of this period, which it will be noted is well over a year, there were still no indications of rancidity. These results further illustrate the remarkable antioxidant properties of the preferred class of materials. In addltlon certain of the compounds. as hereinbefore stated, possess bleaching properties toward omdizable fatty materials. For example tri tolyl phosphite and tolyl phosphorous acid dichloride B were observed to remove slight discoloration from both soap and vegetable oils. The straight ali= phatic esters, as for example tri ethyl phosphite, were found as a rule to be less effective sta ers than the esters containing aryl radicals and it 10 is preferred to employ the latter.

Further tests were conducted by other methods recommended for testing antiomdants in oxidla able fatty materials. Thus 0.1% by weight of the preferred class of compounds, for w w tri tolyl phosphite and o-phenylene phosphite respectively were incorporated in olive oil, cottonseed oil, cocoanut oil and peanut oil. The oils were then emulsified with water and folded pieces of cotton gauze were saturated with the emul- 2c slons and placed in a 4 ounce screw top bottle and heated at 50 0., a procedure described in the Dyestuif Reporter, vol. 26, No. 14, p. 381. Observations were made at the end of cash y both as to color and odor and the phosphorous gs esters tested in this manner were shown to exhibit the stabilizing properties typical of the preferred class of materials.

The amount of the selected one or mixture of the preferred substances which may be added to 30 the ordinary soap, or soap stock, or ingredients used in the manufacture thereof, for eflecting the desired result may be varied, but in general it will be found that good results may be obtained by adding, upon a weight basis, from 0.01% to as 1.0% of the stabilizing agent to the soap or soap stock.

In operating the present invention, the stabilizing agent may be introduced at any stage of the process of soap manufacture. For example, after 40 the fatty acid has been obtained in the usual manner and has been saponified to produce a soap stock, the products comprising the preferred stabilizers may be incorporated therein. The soap product may then be dried in the usual manner as and may be marked in cakes, flakes, or any other form as may be desired. Further, if desirable the stabilizing agent may be incorporated into the dry soap in the well known crutching process. Moreover, the stabilizing agent may conveniently to be added to the oils, fats or fatty acids before saponiflcation. Again the compounds of the present invention may be employed in conjunction with oxidizable fatty materials including soaps and fatty oils broadly as stabilizers thereof.

Other methods of testing the stability of fatty acid compounds than those specifically disclosed may be employed, as is well known to those skilled in the art to which the present invention pertains. The present invention is limited solely by the following claims attached hereto as part of the specification.

What is claimed is:

1. A soap containing a small proportion of a stabilizer against deterioration and development 65 of rancidity consisting of an ester of a trivalent acid of phosphorus containing at least one aroasses matic carbocyclic ester forming radical linked through oxygen to a phosphorus atom.

2. A soap containing a small proportion of a V where R represents an aromatic carbocyclicester forming radical, X is selected from a group consisting of halogen, hydro ry, OR and R; Y is selected from a. group consisting of halogen, hydroxy, 0B, R and an oxygen atom linked to R; and R is selected from a group consisting of alkyl and aryl radicals.

3. A soap containing a small proportion of a stabilizer against deterioration and development of rancidity consisting of an ester of phosphorous acid, IP(OH):, containing at least one aromatic carbocyclic ester forming radical linked through oxygen to a phosphorus atom.

a. A soap containing a small proportion of a stabilizer against deterioration and development of rancidity consisting of a halogen ester of phosphorous acid, P(OH):, containing at least one aromatic cerbocyclic ester forming radical linked through omgen to a phosphorus atom and at least one halogen atom linked to the said phosphorus atom.

5. A soap containing a small proportion of a stabilizer against deterioration and development of rancidity consisting of a halogen ester of phosphorous acid, P(OH):, containing at least one aromatic carbocyclic ester forming radical linked through orwgen to a phosphorus atom and at least one chlorine atom linked to the said phosphorus atom.

6. A soap containing a small proportion of a stabilizer against deterioration and development of rancidity consisting of a halogen ester of phosphorous acid, P(OH):|, containing two aromatic carbocyclic ester forming radicals linked through oxygen to a phosphorus atom and one chlorine atom linked to the said phosphorus atom.

7. A soap containing a. small proportion of a stabilizer against deterioration and development of rancidity consisting of a halogen ester of phosphorous acid, MOI-1):, containing at least one tolyl radical linked through oiwgen to a phosphorus atom and at least one chlorine atom linked to the said phosphorus atom.

8. A soap stabilized'against deterioration and the development of rancidity by having incorporated therein dl p-toiyl phosphorous acid monochloride.

9. A soap stabilized against deterioration and the development of rancidity by having incorporated therein tri o-tolyl phosphite.

10. A soap stabilized against deterioration and the development of rancidity by having incorporated therein the mono ethanol amine salt of o-tolyl phosphorous acid dichloride.

GEORGE D. MARTIN. 

